This is another Lens that I have in my Collection. It’s made by Vivitar and it’s a 500mm Lens. Pictured here mounted on my Pentax K100D with a 2x Double. The Double Lens increases the Lens to a 1000mm.
I was not happy with the results from the 2x. Seem’d to blur the Image too much. I was advised by others that have this not to use it. Just use the 500mm Lens and you will have better results. I took the advice and tried it out. Much better than having the 2x installed.
Again, this is not a Lens to shoot hand held. It would be very wise to use a Tripod for this kind of Lens. If you don’t, your Image will be blurry, unless you are that steady.